Hoist limit mechanism



May 5, 1953 F. LOCK 2,537,525

HOIST LIMIT MECHANISM Filed June 30, 1949 2 SHEETS-SHEET 1 O l I z a M a a 7, JNVENTOR. A 4 04 k 'j BY I ATTORNEY F. LOCK HOIST LIMIT MECHANI May 5, 1953 2 SHEETSSHEET 2 Filed June 30, 1949 ATTORNEY Patented May 5, 1953 'HOIST LIP/HT MECHANISM Frank Lock, Philadelphia, Ilia .-.assignr.;. to): The fifalev a Towne Manufacturing, Company, Stamford, Coma, a. corporation ,of=.Co11necticut Jipplication June 30, 19 i9gSci ialNol-1025289 9 Claims. (Cl. 254-4173) This-invention relates to ;:.,a- .hoist, iand ymore particularlyto limit means for stopping the operation of the hoist when the loadis raised .toia predetermined position. relatively to the .hoist. Mechanisms of. theparticular classare veryold andare well, known in the art. However, .in general, the limit mechanisms of. the prior]. art are either not positive, or else do not lend themselves to adjustment by movement of the load. Where the, limit mechanisms are not positive, they, are frequently ineffective with resulting damage. Where limit mechanisms arenot readily movable. by, the load theyare subject to rather considerable damage, it being possiblelto; apply part of the lifting stress tothe limit mechanism. Obviously, since the limit mechanism is merely designed to control the operation of the hoist, it cannot bear the stress of the load, so that it is frequently damaged.

As a feature of my invention, limit means are provided that are positive, and yet are adapted for ready movement with the load relatively to the hoist to which the limit mechanism is applied in a manner to avoid acceptance of lifting strains.

As-a particular. feature of the invention I provide limit means that are readily .movable with the. load, the limit means being operable in all positions to which they are movedrelatively to the hoist by the load. As a more particular feature of this part of. the. invention, I providea chain guide that isadapted for sliding movement relatively to a support, the support being itself pivotally movable relatively to the hoist. For this reason, the chain guide is adapted, for swinging movement with the chain-as may be required. However, when the end of the chain and the usual hook strikes the chain guide, the chain guide is then movable relatively to its support to actuate the limit mechanism. Incidentally, while I use a chain as the load lifting medium, it should be understood that my invention applies equally well to other meanssuch as'a cable. The load chain should, therefore, not be considered as limiting my claims and invention.-

I have thus outlined rather broadly the more important features of my invention in' order that the detailed description thereof that follows may be better understood, and in order that my contribution to the art may be better appreciated. There are, of course, additional features of my invention that will be described hereinafter and which will form the subject of the claims appended hereto. Those skilled in the art will apclosure is: hasedmay; readily: be utilizedlas a basis for the; designing of other structures. for. carrying out theseveral .pu rp0ses; of. my. invention. ..It is important, therefore, that the claims .to -be granted meshallbeiof sufficient breadth .toprevent the. appropriation of .my. invention. by. those skilled in .the art.

Referring now to thedrawingsFig. 1 isan ele-.

vationand partial. section. of .a hoist. showing .my invention applied-. thereto. L, Fig. 2: is; a section taken along 1ines2-2 of Fig.1. v.IFig'. 3 isa view of-certainofgthe, partsaofiFig. 2 in a second position. i Fig; lis. a: Sid'jViGWDf'. a part; of the hoistzgassembly looking towardxlilig.v 2: from :.the left of said .figure. Fig; 5 is a section takenalong lines 5--5 of Rigel.

. Referring now more particularly, .tojthe drawingsand especially Figs. 1 and 2, there is'shown a aconventional .hoist .utilizing a load .sheave adapted for rotation by theusual motor M carried bythe hoist .and suitable gearing G, all as. .is well known-by.thoseskilled. in the art. .In the particular hoist illustrated, I' use a load: sheave Ilicooperatir g with a. chain II for movingthat chain incpposed.directions-a load hook 12 being attached to one end of the chain 1 I, and a second load hook it being attached to the other end of chain H.

In actual operation, suitablecontrol means are used for controlling theprotation ,of .the load sheave; Hlby themotor Mso that when rotating inone direction, it'will lift. one of the load hooks whileiowering. the other hook,: thereby lifting a. load on onejhooknas the other hook moves downwardly. 'Upon reversalof. rotation, the load sleevelfl'will' actuate the'chain H to lift that hook thathas; earlier been lowered so as to raise the load that'may havebeen-appliedto the hook.

vIt naturally becomes important to stop the operation-of. the motor M when one of the hooks is moved to. itspextremeiupper position, as for example,thehook 121m Fig- 2. 'Where, as in the" case: of hook 12 in Fig. 2,.the chain moves in a vertical-plane, it is'possible to use almost any positive type: of limit mechanism to be contacted by thel 'hook assembly when that. hook assembly reaches its. extremeupperposition. Where the hook and chain .arepat. anxanglazas in the case ofjtherright hand hook. l3-0f Fig. 2, due to the factlthatthe. loadis. at an angle, means must be.provided,forqallowingesuch movement of the chain:and book without .destroying or damaging the limit mechanism. Thus, .the limit mechanismshould. so bedesigned'that'it .will be operpreciatev that the conception on which mycdis- 255; ated...accurately:and without strain" or damage,

whether or not the load is lifted in a vertical plane as by the hook I2, or in an angular direction as by the hook I3. Through my contribution to the art, I provide limit mechanism that is correctly and positively operated regardless of the angular position of the chain in one plane thereof. It will be understood by those skilled in the art that the chain may move in two planes, but that in its movement in a plane at right angles to that of Fig. 2, it merely tends to tilt the hoist on its mounting means.

In my invention, the limit mechanism I have provided is duplicated at each side of the hoist. I shall describe the limit mechanism at one side of the hoist, it being obvious that it is unnecessary to duplicate the description. I provide a shaft I4 supported in bearings I5 on the hoist, and having pivotally mounted thereon a pair of opposed downwardly extending guide and support rods I6. Mounted on each rod I6 is a cylinder II, a spring I8 being contained within each cylinder I! and bearing at one end thereof against a shoulder I9 of shaft I6 while guided by a pin portion I9a formed at the end of each rod I6. Obviously, the springs I8 urge the two cylinders I! downwardly relatively to the rods I6.

The two cylinders I! are bored for opposed stub shafts extending from a chain guide 2I and function thereby to support chain guide 2I for pivotal and sliding movement relatively to the hoist. Chain guide 2I is formed as seen best in Fig. 5 for guiding the chain links. Per se, this guide is not my invention herein claimed.

At one end thereof, one of the stub shafts 2D has pivoted thereto a lever 22 extending upwardly, lever 22 being pivoted at 23 to a further lever 24. Lever 24 is formed with a bored upper end 25 that is suitably keyed or splined to a shaft 26 extending into a switch housing 21. In the switch housing there is contained a controlling contactor 28 of any suitable construction equipped with a switch actuating plunger 29 adapted for coaction with a cam 30 at the end of the shaft 26. It is quite obvious that as the cam 30 rotates through movement of shaft 26 by levers 22 and 24, it will operate the plunger 29 to actuate the contactor 28 and to break the circuit of motor M and apply the usual brake.

In Fig. 2 the left chain guide is shown in that position in which it is normally maintained when a load is lifted vertically by normal actuation of the chain I I. Any additional vertical movement of the hook I2 by the chain II in 2 will, of course, effect vertical movement of the chain guide 2 I, the chain guide moving vertically through the accompanying movement of the cylinders I! on the rods I6 against the resistance of springs I8. This movement of the chain guide 2| will effect movement of lever 22 and the switch operating lever 24 so as to rotate shaft 26 and its cam surface 30 and thereby operate the contactor 28 to break the circuit of the hoist motor.

At the right hand side of Fig. 2 the chain guide 2I is shown in that position to which it is moved by a load applied to the hook I3 with the load displaced vertically relatively to the hoist. It will here be noted that the levers 22 and 24 have been moved away from their normal position but that this has not in any way afiected the operation of the limit switch mechanism. If now the hook is raised by the movement of the chain in the angular direction illustrated, the chain guide 2I will be moved to the dash and dotted line position of Fig. 2 with the switch operating lever 24 rotating the shaft 26 so as to '4 operate the contactor to break the circuit of the motor M of the hoist. It will be readily appreciated that during this movement there has been no strain whatsoever on any part of the limit operating machanism.

In Fig. 3 one chain guide 2I is shown swung to the left of its normal vertical position by the displacement of the chain through the application of the load at the left of the vertical line. If in this position of the parts the chain II is actuated to move the hook I3 upwardly and along the line of the chain, then of course the levers 22 and 24 will be actuated once again, as previously outlined, to break the circuit of the contactor 28. Again it is readily seen that there has been no strain whatsoever on the operating parts of the limit mechanism and that the said limit mechanism has been actuated most eiIectively.

It will now be appreciated that the operation of my limit mechanism is positive, because the hooks I2 and I3 contact their respective chain guides 2I in all positions thereof to effect operation of the levers 22, 24. It is further appreciated that while this action is positive, it is accomplished without imparting strain to the parts of the limit mechanism. Thus, all the force exerted on the chain guide is in a direction tending to move the chain guide in the normal manner for which it is adapted to move relatively to the rods I B and with the cylinders II. It is thought that the considerable merit of my invention will now be fully appreciated.

I now claim:

1. In a hoist of the class described, a hoist body, a chain guide, support means mounting said chain guide for pivotal swinging movement, means mounting said chain guide for sliding movement relatively to said support means, a switch actuating lever pivoted on said hoist body, and an operating member pivoted to said switch actuating lever and to said chain guide for moving said switch actuating lever upon sliding movement of said chain guide on said support means.

2. In a hoist of the class described, a hoist body, a chain guide, support means mounting said chain guide for pivotal swinging movement, means mounting said chain guide for sliding movement relatively to said support means, a switch actuating lever pivoted on said hoist body, an operating member pivoted to said switch actuating lever and to said chain guide for moving said switch actuating lever upon sliding movement of said chain guide on said support means, and spring means resisting sliding movement of said chain guide in one direction on said support means.

3. In a hoist of the class described, a hoist body, a chain actuator, a chain guide having a through passage for guiding a chain as it is moved longitudinally past said guide by said actuator, a pair of rods pivoted on said hoist body for swinging movement, bearing means secured to opposed portions of said chain guide and slidably mounted on said rods, the pivotal movement of said rods and the mounting of said bearing means thereon aligning said chain guide with the chain actuator and the load in all positions of the load, spring means yieldingly maintaining said bearing means in one end relation to said rods, switch actuating means moved by sliding movement of said chain guide and bearing means on said rods, and means mounting said switch actuating means on said hoist body independently of said rods..

4. In a hoist of the class described, a hoist body, a chain guide having a through passage for the movement of a chain, a rod pivoted on said hoist body, means slidably mounting said chain guide on said rod, a limit switch on said hoist body, a limit switch actuating lever movably mounted on said hoist body, an operating member pivoted to said switch actuating lever and to said chain guide for moving said switch actuating lever upon sliding movement of said chain guide on said rod, and spring means resisting sliding movement of said chain guide in one direction on said rod.

5. In a hoist of the class described, a hoist body, a support rod pivoted on said hoist body and hanging vertically downwardly relatively to said hoist body when said hoist body is supported in its normal operating position, a chain guide, means slidably mounting said chain guide on said rod, a limit switch on said hoist body, a limit switch actuating lever movably mounted on said hoist body, an operating member pivoted to said switch actuating lever and to said chain guide for moving said switch actuating lever upon sliding movement of said chain guide on said rod, and spring means resisting sliding movement of said chain guide in one direction on said rod.

6. In a hoist of the class described, a hoist body, a chain actuator, a chain guide for guiding a chain as it is moved longitudinally past said guide by said actuator, support means mounting said chain guide for pivotal swinging movement on said body by said chain as said chain moves relatively to said guide, means mounting said chain guide for sliding movement relatively to said support means independent of the pivotal movement of said support means, the pivotal movement of said support means and the mounting of said chain guide thereon aligning said chain guide with the chain actuator and the load in all positions of the load, and switch actuating means mounted on said hoist body independently of said support means and moved by sliding movement of said chain guide on said support means.

7. In a hoist of the class described, a hoist body, a chain actuator, a chain guide for guiding a chain as it is moved longitudinally past said guide by said actuator, support means mounting said chain guide for pivotal swinging movement on said hoist body by said chain as said chain moves relatively to said guide, means mounting 3 said chain guide for sliding movement relatively to said support means independent of the pivotal movement of said support means, the pivotal movement of said support means and the mounting of said chain guide thereon aligning said chain guide with the chain actuator and the load in all positions of the load, spring means resisting sliding movement of said guide in one direction on said support means, switch actuating means moved by sliding movement of said chain guide on said support means against the pressure of said spring means, and means mounting said switch actuating means on said hoist body independently of said support means.

8. In a hoist of the class described, a hoist body, a chain, a chain actuator, a chain guide having a through passage for guiding said chain as it is moved longitudinally past said guide by said actuator, a rod pivoted on said hoist body, means slidably mounting said chain guide on said rod whereby said chain through the pivotal movement of said rod aligns said chain guide with a straight line passing from the load to the chain actuator in all positions of the load, means on said chain for sliding said chain guide on said rod, and switch actuating means moved by sliding movement of said chain guide on said rod.

9. In a hoist of the class described, a hoist body, a chain, a chain actuator, a chain guide having a through passage for guiding said chain as it is moved longitudinally past said guide by said actuator, a rod pivoted on said hoist body, means slidably mounting said chain guide on said rod whereby said chain through the pivotal movement of said rod aligns said chain guide with a straight line passing from the load to the chain actuator in all positions of the load, spring means resisting sliding movement of said chain guide on said rod, means on said chain that strikes the guide to move it relatively to said rod, and switch actuating means moved by sliding movement of said chain guide on said rod.

FRANK LOCK.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 836,789 Vance Nov. 27, 1906 1,113,593 Wright Oct. 13, 1914 1,553,607 Garrigan Sept. 15, 1925 1,890,539 Hallenbeck Dec. 13, 1932 2,335,568 Lock Nov. 30, 1943 2,434,138 Adams Jan. 6, 1948 

